Y-Tong (aerated concrete) - quality building material? (sound insulation!)

Somehow a few posts have passed me by here, sorry. Meanwhile, I can say the following. We will build with the 36.5 Ytong and have ordered soundproof windows of class III. Both the architect and the window manufacturer thought that this was totally fine. Outside we also have filled aluminum shutters. I just think that even a sand-lime brick won't help if the windows only have "35-39 dB" - or am I wrong?

We also now live in a timber frame new build from 2017 and the noise from the main street comes through the windows, not through the house wall.

The bedroom is on the other side of the noise source, so we are basically quite relaxed there.

We now also find the clinker variant directly on the Ytong quite appealing outside, so we are still thinking about that. That should be sufficient for a 30 km/h one-way street in the village with cobblestones.

Inside the construction specification says the following: "The non-load-bearing interior walls are made as metal stud walls with UW + CW profiles and a double plasterboard cladding. The required sound insulation is achieved with 60 mm thick mineral fiber insulation. The masonry knee walls are clad with a single layer of plasterboard." ==> my question here: is that okay?

We have looked at a house of a private builder with the general contractor and found everything quite tidy. The interior walls seemed solid and "soundproofing".

"The non-load-bearing interior walls are constructed as metal stud walls with UW + CW profiles and a double sheathing in drywall. [...] The masonry knee walls are covered with a single layer of drywall." ==> I have a question about this: is that okay?

Double sheathing is "standard" for metal profile drywall walls in residential buildings; for masonry walls, a second sheathing layer is unnecessary. Where are the knee walls supposed to be installed?

Where are knee walls supposed to be placed?

I just copied it like that. The construction performance description has not yet been fully adapted to us. I myself had to google it once to find out what it is. It is probably not relevant for two full stories.

We build 17.5 cm Ytong plus insulation and render it. Total thickness 45 cm

Inside 11.5 cm lime sandstone. That is standard everywhere here.

This is standard everywhere here.

But there are also some who build entirely with KS, and some others offer it for the exterior walls as an alternative to aerated concrete.

There are also some who build completely with KS, others offer it for the exterior walls as an alternative to aerated concrete.

Yes, that's true.

Then you need more insulation.
That's probably good too.